Mercury boiler



Feb. 2, 1937. A R SMITH 2,069,629

MERCURY BOILER Filed Sept. 21, 1934 2 Sheets-Sheet 1 Fig.

Inventor; Ar'th UT 9.5m ith,

is Attorney Feb. 2, 1937. sMlTH 2,069,629

MERCURY BOILER Filed Sept. 21, 1954 2 Sheets-Sheet 2 lhven'tor Arthur F2.Srnith,

His A orneg Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE MERCURY BOILER Arthur R. Smith, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York The present invention relates to mercury boilers comprising a drum or drums or like containers and heating elements connected thereto for heating and evaporating mercury liquid. In the usual power plant the available energy of the mercury vapor thus produced is utilized in turbines or like apparatus and the exhaust of the turbines is condensed and returned or fed to said drums or containers. The amount of mercury in such power plants remains substantially constant and the liquid level in the drum or drums varies little during normal operation. My invention relates more specifically to the kind of mercury boilers in which a mixture of mercury and another substance, such as aluminum or sodium, is used for operating the boiler. The addition of such other substances to the mercury improves considerably the operation of mercury boilers.

The operation of boilers of the type just specified has shown that the mixture does not remain uniform in the different parts of the boiler.

After a certain period of operation the concentration of the mixture, that is, the sodium content per unit mercury increases in one part, and decreases in another part of the boiler. Decreasing concentration in certain parts of the boiler is detrimental in that it reduces to a considerable extent the capacity of such parts. For example, a boiler heating element which normally carries a load of, let us say, 100 kw. can carry safely only a small fraction of this load if the amount of sodium or like ingredient decreases below a fixed minimum. In a certain boiler which comprises longitudinal drums, to which mercury is fed at the ends of the drums, it has been found that after a certain period of operation the concentration increased in central portions of the drum space whereas it decreased near the end portions. Furthermore, it was found that the content of sodium or like substance increased in certain drums as a whole and decreased in other drums. For example, it was found in a boiler having a plurality of drums that the average amount of ingredient in some of the drums was half only and less than in other drums. The reason for this change in concentration in the individual drum and with respect to the different drums is the following: The substances added to the mercury to improve the operation of the mercury boilers have a boiling point above that of the mercury liquid so that at the operating temperature of the boiler at which the mercury is evaporated, said substances remain in liquid state. The mercury vapor produced as stated before is passed through a turbine or the like and returned as their diameter.

condensate to the drums and like containers of the boiler. It is important to note that the drums of the present type mercury boiler are cylindrical in shape and of a length several times that of The mercury fed to the ends of the boiler contains little of such substances, to the effect that the concentration near the ends of the boiler decreases considerably, whereas the concentration in the central portion of the boiler increases correspondingly. This explains clearly I the change in concentration within the individual boiler drum. As to the change in concentration between different drums, it has been found that during evaporation and discharge of vapor from the drum, a certain amount of such other substances as sodium, aluminum or the like is carried away by the moisture content of the vapor. The discharge of vapor from the different drums is not uniform. Some of the drums discharge more, others less, to the effect that more of the added substance is carried away from one drum than from another drum. Also the supply of liquid to the drums is not uniform. Some of them receive more, others less, depending upon the pressure in the drums and the resistance to flow met with in the conduits for conducting liquid tothe drums. All these various factors tend to reduce the uniformity of the mixture within the several containers of a mercury boiler, with the injurious results pointed out above. Heating elements containing liquid with too low concentration of mercury and such other substance soon become overheated and can no longer safely carry their intended load.

The object of my inventionis to provide an improved construction and arrangement of mercury boilers for maintaining the mixture of mercury and such other substance uniform throughout the boiler, more particularly throughout all elements of the boiler in which mercury is heated and evaporated. From another viewpoint, the object of my invention is to provide an improved construction and arrangement of mercury boilers in which the non-uniformity of mercury and such other substances is reduced. From still another viewpoint, the object of my invention is to provide an improved construction and arrangement of mercury boilers in which the substance added to the mercury is uniformly distributed throughout the boiler.

This is accomplished in accordance with my invention by the provision of means for conducting operating fiuid from one point of the boiler to another point thereof, more specifically, for conducting operating fluid from a point of highabove the normal liquid level in a drum and,

er concentration to a-point of lower concentration, or vice-versa. In a boiler comprising a plurality of drums, such means are provided with respectto each individual drum and a-lso'with're spect to different drums, that is, means are provided for conveying operating fluid from a point of high concentration within an individual drum to a'point of lower concentration in the same drum, and other means are provided for conveying operating fluid from one drum to another drum. The conveying of liquid from one point of the boiler to another in a preferred embodiment of my invention is accomplished by means utiliz ing the energy of ebullition, for instance, ,by. the

provision of a trough or likecontainer disposed adapted to receive and collect liquid from the drum which is forced up to a'higher level than the normal liquid level by the energy of ebullition. The liquid thus collected in such trough or container is conducted by suitable conduit means to another point of the same drum or anotherdrum. V V

For afibetter understanding of what I believe to be novel and my invention, attention 'is' directed to the following description and the claims appended thereto in connection with the accompanying drawings. r

In the drawings, Fig. lis adiagrammatic front view of a 'boilerjFig. 2 is a perspective view partly'in sectionof an individual drum; and Figs. 3

and 4' are sectional views along lines '3- 3 and 44 respectively of Fig. 2.

The mercury boiler comprises a furnace having a-wall I 0 and a plurality of drums, in the present instance seven-drumsfl l,l2, I3, l4; l5, I6

and H projecting through the furnace wall 10. Liquid is supplied to the drums by a liquid supply conduit 18 which is directly connected to the ends of each drum byconduits 19 (Figs. land 2),

and vapor-is discharged from the drums through 'a common vapor discharge conduit 20'connected to each drum by a conduit 2|. With respect to the supply of liquid from the liquid supply conduit 18, it is important to note that no other elements arei-nterconnected between the con- ;duit "l8 and the drums whereby an equalizing 'effeet as to the supply of liquid to the different drums is accomplished, that is, liquid flows from the conduit [8 to the difierent drums in accordance with the load on said drums. It has been found that in 'a boiler :of the kind indicated, the outer drums "I! and I2 carry somewhat higher loadthan the intermediate drums 12 to Hi inelusive; With the liquid supply arrangement as shown, more liquid flows into said outer drums H and I1 than into the intermediate drums.

The lower portion of each drum is' connected to heating elements in the form of porcupine tubes 22; The outer drums H and 11 in addition are connected to other heating elements in the form of wall screen heating elements 23. The porcupine tubes '22 comprise an outer tube 24 conbrackets 42.

ment block 30 is disposed within each drum to reduce the amounts of liquid necessary to operate the boiler. This displacementblock, as clearly shown in Fig. 2, comprises a plurality of sec.

Qtions which are fastened to the outer 'wall 25 by means of bolts 3|. A section 32 near the head of the drum is cut away to form channels and '35. These channels are adjacent the ends of the During operation of the boiler, liquid flows into the porcupine tubes through their inner tubes l6 and is heated and partly evaporated up-tubes 29 of the wall screen heating elements within thespace defined between the inner tubes.

26 and the-outer tubes 24. The liquid discharged from the porcupine tubes isrecirculated whered as the vapor discharged flows through the vapor outlet conduits 2|. Similarly, liquid flows through the down-tubes 28 of the wall-screen element and is heated and partlysevaporated in the up-t-ubes 29 =the,.liquid being recirculated and the vapor discharged from the drum. Liquid vapor separating means are provided in the upper portion of each drum to minimize the amount of liquid carriedalong by the vapor. This liquid vapor separating means as shown in Fig. 4 comprises a metal sheet 36 having outer portions fastened to the wall 25 and an intermediate portion provided with perforations 31.

the mixture of liquid and vapor is forced up by the energy of ebullitionfthe outer' portions of the-sheet 36, which in substance form deflectors, cause the liquid content of the mixture tobe deflected in downward'directio'n while the vapor escapes through the mediate portion. 7 V

In the present arrangement, liquid is "conducted toboth ends of each drum through conduits 19 (Fig. 2). The liquid fed to the drums is comparatively pure, containing a amount only of such other substance assodium, aluminum or the like. The, continuous supply of comparatively-pure mercury liquid to the end of the drums after a short time causes a change in concentration within the individual drum,

that is, a low concentration near the ends of the drums and a high concentration'near the central portions of the drums. V This ordinarily would perforations V '31 of the inter! small s10 7 lead to overheating 'of the heating elements con 7 nected to said end portions of the drum, in the i present instance to the overheating of some of the porcupine tubes 22 and to the overheatingof the up-tubes 29 of the'wall screen elem'ents' 23. fThis change in concentration isprevented or, from another view point, the non-uniformity Within the drums is reduced by the provision of means for conveying operating fluid between the end portions and the central or in- V termediate portions of eachdrum'. This means comprises four troughs 38, 39, 40 and M, fastened to the displacement block 30,by' means of forming a container and a, deflector 44 secured to the wall 43.' Each trough is connected to one end of a conduit 46, which conduit has its other end disposed near an end portion of "the drum.

Each trough comprises a wall 43' In the present instance the conduits of the j troughs 38 and 39 have'their end'portions ,disposed in the front end'portion of the drum and the ends of the conduits connected to the troughs 49 and 4| aredisposed in the rearend portion of the drum.- Furthermore, the troughs are disposed at difierent levels. In the present instance the troughs 38 and 40 are disposed at a high r v l t an the troughs 39 and M, but all troughs are disposed at levels above the normal liquid level in the drum. The purpose of disposing different troughs at difierent levels is' to take care of normal level variations Within the drum. Each trough with a conduit forms in substance a scupper, that is, a means for conveying liquid'from one point in the drum to another point, in the present instance from a point of high concentration near the center of the drum to a point of low concentration near the end of the drum. From another viewpoint, said troughs and conduits may be considered as stirring means for stirring or setting in motion the mixture of mercury and such other substance to maintain the mixture uniform. During operation, liquid is discharged from the heating elements into the drums in the form of streams to levels above the normal liquid level in the drum. The velocity energy of these streams which is the energy of ebullition is utilized to carry liquid from one point to another. More specifically, the operating fluid as it shoots up in the form of streams is collected in the troughs whereby its velocity energy is partly preserved in the form of potential energy. From the troughs the fluid flows along the tubes connected to the troughs toward the ends of the drum. In the present instance, as stated before, part of the streams of liquid discharged from the porcupine tubes near the central portion of the drum are discharged into the troughs 38 to M. The streams during their upward flow are deflected by the deflectors 44 whereby the liquid is discharged into the troughs While the vapor may escape through the vapor outlet conduits of the drums. Under normal operating conditions all four troughs 38 to 4! are operative, that is, act to carry liquid from central portions of the drum towards end portions thereof. If the level rises under certain operating conditions above the inlet edges 50 (Fig. 4) of the troughs 39 and 4|, these troughs become inoperative and the carrying of liquid from intermediate portions to the end portions thereafter is performed by the troughs 38 and 40 only.

The means for carrying liquid from one drum to another drum comprises a trough 5! disposed above the recessed block section 32. A deflector 52 having two curved sections 53 and 54 is disposed above the trough 5| and held in position by projections 55 slidably supported by the wall 25 of the drum. The slidable support of the projections 55 permits relative expansion between the deflector and the wall of the drum. With this arrangement, fluid discharged from the up-tubes 29 of the wall screen heating elements is deflected by the deflector 52 so that the liquid is discharged into the trough 5I while the vapor may escape through the outlet conduit of the drum. The trough 5| is supported by brackets 56 secured to the block section 32 by bolts 57. The trough is connected by a conduit 58 (Figs. 2 and 3) to another drum so that liquid contained in the trough may flow therefrom by gravity to such other drum. In the present arrangement (Fig. 1) I have provided conduits for conducted liquid from drum I4 to drum I3, from drum I3 to drum I2, from drum I2 to drum II, from drum I I to drum I4, from drum I4 to drum I5, from drum I5 to drum I6, from drum I6 to drum I! and finally, from drum II to drum I 4. Thus the drums are all interconnected by this auxiliary means for conveying fluid from one point of the boiler to another point or points to increase the uniformity of the mixture or,

from another viewpoint, to maintain the mixture uniform. Also in this case the energy of ebullition is utilized. The streams of fluid discharged from the tubes 29 are collected at a level above the normal liquid level whereby their kinetic energy is preserved in the form of potential energy and this potential energy causes operating fluid toflow from one point of the boiler to another.

With my invention I have provided an improved construction and arrangement of mercury boilers, using a mixture of mercury and other substance as operating fluid whereby the mixture is maintained uniform, assuming that uniformity of the mixture exists at the beginning of the operation. In case non-uniformity exists at the beginning of the operation, for instance, when a substance such as sodium or aluminum has been added to the mercury in a single drum, my invention represents an arrangement for increasing the uniformity or, from another viewpoint, for effecting uniform distribution of the other substance in the different parts of the boiler exposed to external heat.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A mercury boiler using a mixture of mercury and another substance as operating fluid including a drum, heating elements connected to the drum for containing and heating operating fluid, means for conducting mercury to one portion of the space defined within the drum, and means for conveying operating fluid between said portion and another portion during operation to maintain the mixture uniform, said means comprising at least two scuppers having troughs disposed at different levels in one of said portions for receiving liquid discharged from the heating elements to a level above the normal liquid level by the action of ebullition and discharge conduit means for the troughs having one end connected to the troughs and another end disposed in the other of said portions whereby the energy of ebullition is utilized for conveying liquid from one point of the drum to another point.

2. A mercury boiler using a mixture of mercury and another substance as operating fluid including a drum, a conduit for conducting mercury liquid to the drum heating elements connected to the drum for containing and heating such mixture, a trough disposed in the drum above the normal liquid level and receiving liquid discharged from the heating elements to a higher level in the drum by the action of ebullition, and means for conducting liquid from said trough to a point of the boiler near the connection between the drum and the conduit to maintain the mixture substantially uniform.

3. A mercury boiler using a mixture of mercury and another substance as operating fluid including a drum, heating elements connected to the drum for containing and heating such mixture, means for conducting mercury toend portions of the space defined in the drum, two troughs disposed at different levels intermediate said end portions above the normal liquid level in the drum for receiving liquid discharged to a higher level from the heating elements by the action of ebullition, and means for conducting liquid from the troughs towards the end portionsof the drum to maintain the mixture uniform. V n V 4. A mercury boiler.using a mixture of mercury and another substance as operating fluid including a plurality of drums and heating; elesaid means comprising-a trough disposed in zone drum at a level above the normal liquid level for receiving liquid dischargedfrom the heating -ele- .ments to a higher levelby the action 01 ebullition and a conduit connected atone end to the -5 trough and at'the other end to another drlum V at a level below the level of the trough.

ARTHUR B. SMI'I'I-I. 

